Wide assortments of implantable medical devices are presently known and commercially available. These implantable medical devices include a variety of implantable cardiac devices. For example, implantable pulse generators (IPGs) are a type of cardiac device that is generally used to elevate the heart rate that is beating too slowly. This type of device is sometimes referred to as a Bradycardia device or a pacemaker. Another type of implantable cardiac device is an implantable cardioverter defibrillator (ICD). This type of device, often referred to as a Tachycardia device, generally provides burst pacing pulses or a defibrillation shock to the heart when the heart is beating too fast or goes into fibrillation. Another type of device is a cardiac resynchronization device that treats heart failure. Another type of device are monitoring devices that use one or more physiologic sensors.
Each of these types of implantable medical devices requires the use of several components to provide the desired functionality. For example, a typical implantable medical device includes one or more sensing devices (e.g., magnetic sensor, pressure sensor, motion sensor, ECG sensor), processors, data storage devices, patient alert devices, power management devices, signal processing and other devices implemented to perform a variety of different functions. The various subsystems require mechanisms to communicate between subsystems in the device. For example, a typical implantable medical device requires reliable communication between a variety of different sensing devices and a main processor. Other types of communication can include event and message communication.
Each of these different types of communication can have different requirements. Again, to use the example discussed above, communicating between sensing devices and the main processor can require periodic communication reliability delivered at precise time intervals to reduce jitter in the sensing data. In contrast, general message communication between subsystems typically does not require such precise timing delivery, but it can require the ability to send much larger messages.
Unfortunately, mechanisms for communicating between subsystems in implantable medical devices lack flexibility to effectively provide for different types of communication between subsystems without requiring a substantial redesign of the communication system and of the subsystems themselves. Thus, there remains a need for improved communication systems in medical devices that facilitate communication between subsystems, including the ability to deliver different types of data with different delivery requirements, while maintaining design and implementation flexibility.